In roll mills, the roll surfaces, in particular in the case of roll presses, are frequently protected by profile bodies. To this end, cylindrical hard metal pins are very frequently used in practice which are introduced into a soft basic matrix and form an autogenous wear protection layer with the material to be ground. Roll mills of this type are used for grinding limestone, dolomite or other brittle materials, such as during the processing of ore.
Roll mills of this type are usually reconditioned at regular intervals of, for example, 12 months. Down times in the case of the mills which are as a rule very large have to be kept as low as possible for reasons of economy. As a result of locally increased wear or as a result of the loss of individual hard metal pins, however, pronounced erosion can occur at said locations, with the result that the basic material of the roll main body is damaged irreparably and renewed reconditioning is no longer possible and the complete roll has to be conditioned or even replaced. In practice, regular visual checks are therefore carried out.
DE 10 2007 004 004 A1 has disclosed a roll mill having two grinding rolls which are driven in opposite directions, each grinding roll having a roll main body which is fitted with a multiplicity of profile bodies. Furthermore, a monitoring apparatus is provided which checks the wear state of the multiplicity of profile bodies and detects any wear at an early stage. A wear prognosis of the roll surface is derived herefrom, in order for it to be possible to plan the next reconditioning in good time, with the result that unnecessary down times are avoided.
Since the reconditioning of a grinding roll is made possible only with relatively great outlay which often also requires transport to central conditioning stations, the usual reconditioning intervals are already set with a relatively long lead time, with the result that unplanned conditioning often cannot be carried out promptly. Secondly, premature reconditioning of the grinding roll is also to be avoided as far as possible from an economical aspect. One therefore often makes do with the improvement of individual locations which can be carried out on site.